One or two of five code rotary magnetic position indicator

ABSTRACT

A rotary magnetic position indicator for displaying 10 discrete indicia in response to a one or two of five code or a one of five reverse polarity code. A stator core has a yoke with 10 equally spaced, inwardly extending teeth having inner ends defining a bore. A permanent magnet rotor member is rotatably mounted in the bore and has oppositely polarized diametrically opposite ends each spanning the inner ends of three stator teeth and forming air gaps therewith. Five identical field windings are provided each having first and second ends and each comprising first and second coils on the yoke, there being one coil between each different pair of teeth and the two coils of each different winding having a different group of three teeth therebetween. The first end of each different winding is connected to a different external terminal and the seconds ends of all the windings are connected to a common terminal. The windings are arranged so that upon connection of each different one of the external terminals and the common terminal to a source of direct current, a different group of three adjacent teeth are excited with one polarity, and so that upon connection of the external terminals respectively connected to each different pair of adjacent windings and the common terminal to the source, a different group of five adjacent teeth are excited with one polarity with the middle one of the group of five teeth having a higher magnetic flux density therein than the remaining projections of the group.

United States Patent 1 Harden [54] ONE OR TWO OF FIVE CODE ROTARYMAGNETIC POSITION INDICATOR Phillip L. Harden, Ft. Wayne, lnd.

[73] Assignee: Bowmar Instrument Corporation,

Ft. Wayne, Ind.

[22] Filed: Nov. 19, 1971 [21] Appl. No.: 200,316

[75] Inventor:

Primary Examiner-Harold I. Pitts Attorney-Harold B. Hood, George A.Gust, Robert G. Irish et a1.

[57] ABSTRACT A rotary magnetic position indicator for displaying 1Odiscrete indicia in response to a one or two of five code or a one offive reverse polarity code. A stator core has a yoke with 10 equallyspaced, inwardly extending teeth having inner ends defining a bore. Apermanent magnet rotor member is rotatably mounted in the bore and hasoppositely polarized diametrically opposite ends each spanning the innerends of three .stator teeth and forming air gaps therewith. Fiveidentical field windings are provided each having first and second endsand each comprising first and second coils on the yoke, there being onecoil between each different pair of teeth and the two coils of eachdifferent winding having a different. group of three teeth therebetween.The first end of each different winding is connected to a differentexternal terminal and the seconds ends of all the windings are connectedto a common terminal. The windings are arranged so that upon connectionof each different one of the external terminals and the common terminalto a source of direct current, a different group of three adjacent teethare excited with one polarity, and so that upon connection of theexternal terminals respectively connected to each different pair ofadjacent windings and the common terminal to the source, a differentgroup of five adjacent teeth are excited with one polarity with themiddle one of the group of five teeth having a higher magnetic fluxdensity therein than the remaining projections of the group. 1

19 Claims, 11 Drawing Figures Patented May 29, 1973 6 Sheets-Sheet 1 IFIG! COM MON INVENTOR! PHlLLlP L..HARDEN, BYWMMM* I ATTORNEYS.

Patented May 29, 1973 3 ,736,588

6 Sheets-Sheet 3 AB c o E coM.

d) m I (7 Ul w M O c FIG.6

INVENTORZ F ATTORNEYS.

PHILLIP L. HARDEN,

Patented May 29, 1973 3,736,588

6 Sheets-Sheet 4 READING A B C D E F COM.

I 3 FIG. 7 4

FIG.8

INVENTOR. PHILLIP L. HARDEN,

. E BY W ATTORNEYS.

Patented. May 29, 1973 6 Sheets-Sheet 5 FIGS) Patented 'May2 9, 1973 6Sheets-Sheet 6 E :m e

A mH N. EL v mp u u H P ATTORNEYS.

ONE OR TWO OF FIVE CODE ROTARY MAGNETIC POSITION INDICATOR BACKGROUND OFTHE INVENTION 1. Field of the Invention This invention relates generallyto rotary magnetic position indicators, and more particularly to rotarymagnet position indicators of the type which respond to a one or two offive code or a one of five reverse polarity code.

2. Description of the Prior Art Rotary magnetic position indicators arecommonly employed for displaying discrete indicia in response to thecharacters of a prearranged code. A common type of such indicatorcomprises a diametrically polarized permanent magnet rotor and a statorstructure having selective energizable field windings thereon, the rotorcarrying a drum having the indicia displayed on its sur face. Selectiveenergization of the field windings causes the magnetic axis of the rotorto align itself with the respective poles of the field structure whichare energized, thereby to provide the desired rotational indication.

A common form of rotary magnet position indicator for displaying ldiscrete indicia, such as the numerals 0 to 9, is provided with fivefield windings respectively connected to five external terminals and acommon terminal and responding to a one or two of five code or a one offive reverse polarity code. In the case of a one or two of five code,energization of each different one of the five windings provides five ofthe rotational positions and energization of different pairs of thewindings provides the remaining five positions. In a one of five reversepolarity code, energization of each different one of five windings withcurrent flow in one direction provides five of the rotational positionsand energization of each different one of the windings with current flowin the reverse direction provides the remaining five positions. Thereare also instances where it is desired to provide a rotary magneticposition indicator displaying some other even number of discreteindicia, such as 12, in response to a similar code, Le, a one or two sixcode or a one of six reverse polarity code.

Prior rotary magnetic position indicators responding to a one or two offive code are shown for example in IBM Technical Disclosure Bulletin,Volume 2, No. 2, August, 1959, Page 7, and in U.S. Pats. No. 3,441,927to LA. Watkins, No. 3,376,569 to J.A. Watkins, No. 3,350,079 to L.C.Pursiano et al. and No. 3,311,911 to LC. Pursiano et al. U.S. Pat. No.3,416,015 to A.F. Ordas and assigned to the assignee of the presentapplication discloses a rotarymagnetic position indicator wherein 180rotation of the rotor member is assured by angularly offsetting themagnetic axis from the geo metric axis of the rotor.

SUMMARY OF THE INVENTION The invention, in its broader aspects, providesa rotary magnetic position indicator for displaying a predetermined evennumber of discrete indicia, the indicator comprising a magnetic statorcore structure having a yoke portion with the same even number of polarprojections extending radially inwardly therefrom, the projections beingequally angularly spaced around the yoke portion and having radiallyinner ends defining a bore. A magnetized rotor member is mounted in thebore for rotation about an axis concentric therewith and havingoppositely polarized diametrically opposite ends, each of the oppositeends having an angular span generally equal to the angular span of theinner ends of three adjacent stator projections and forming air gapstherewith. A polarity of substantially identical field windings equal innumber to one-half the same even number and each having first and secondends are positioned on the core structure in angularly displacedsymmetrical relationship. Each of the windings has its first endconnected to a different external terminal adapted to be selectivelyconnected to one side of a source of direct current potential, thesecond ends of all of the windings being connected to a common terminaladapted to be connected to the other side of the source. The arrangementof the windings is such that upon connection of each different one ofthe external terminals and the common terminal to the source andenergization of the respective winding thereby, a different group ofthree adjacent projections are excited with one polarity thus causingthe rotor member to rotate to align its opposite polarity end with therespective group of three projections, and that upon connection of theexternal terminals respectively connected to each different pair ofadjacent windings and the common terminal to the source andenergizationof the respective pair of adjacent windings thereby, adifferent group of five adjacent projections are excited with onepolarity with atlea st the middle one of the: group of five projectionshaving a higher magnetic flux density therein than the outer two of thegroup of five projections thereby causing the rotor member to rotate toalign its opposite polarity end with the middle three of the respectivegroup of five projections, thus providing the predetermined even numberof discrete magnetic orientations for the rotor member.

It is accordingly an object of the invention to provide an improvedrotor magnetic position indicator for displaying a predetermined evennumber of discrete indicia.

Another object of the invention is to provide an improved rotarymagnetic position indicator of the one or two of five, or one of fivereverse polarity code type.

A further object of the invention is to provide an improved permanentmagnet rotor member for a rotary magnetic position indicator fordisplaying a predetermined even number of discrete indicia.

The above-mentioned and other features and objects of this invention andthe manner of attaining them will become more apparent and the inventionitself will be best understood by reference to the following descriptionof an embodiment of the invention taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side cross-sectional viewshowing one embodiment of the invention;

FIG. 2 is a top view, partly in cross-section, showing the stator androtor assembly of the indicator of FIG. 1, and also schematicallyshowing the field winding coils and connections therebetween andthereto;

FIG. 3 is an enlarged view of the permanent magnet rotor of theembodiment of FIGS. 1 and 2;

FIG. 4A is a chart showing a one or two of five code which may beemployed with the embodiment of FIGS. 1 and 2;

FIG. 4B is a chart showing the coils of the embodiment of FIGS. 1 and 2which are energized in response to the code of FIG. 4A;

FIG. 5 is a chart showing a one of five reverse polarity code which maybe employed with the embodiment of FIGS. 1 and 2;

FIG. 6 is a view, similar to FIG. 2, showing a 12 position indicatorincorporating the invention;

FIG. 7 is a chart showing a one or two of six code which may be employedwith the embodiment of FIG.

FIG. 8 is a schematic diagram showing another embodiment of theinvention;

FIG. 9 is a schematic diagram showing a further embodiment of theinvention;

FIG. 10 is a schematic diagram showing yet another embodiment of theinvention; and

FIG. 1 1 is a schematic diagram showing a still further embodiment ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS Referring now to FIGS. 1 through 3 ofthe drawings, there is shown a rotary magnetic position indicator,generally indicated at 20, for displaying ten discrete indicia, such asthe numerals zero through nine, in response to the characters of a oneor two of five code such as shown in FIG. 4A, or a one of five reversepolarity code, such as shown in FIG. 5. Indicator comprises base plate22 which may be a printed circuit board carrying the connections to andbetween the coils. Shaft 23 has end 27 seated in opening 28 in baseplate 22 and has flange 30 adhesively secured thereto. The statorstructure of the indicator comprises core 24 formed of suitable magneticmaterial having yoke portion 25 with 10 radially inwardly extending,equally angularly spaced polar projections or teeth formed thereonrespectively identified as 1' through 10. The polar projectionsrespectively have inner ends 26 mutually defining a bore. Core 24 issupported on base plate 22 by a plurality of insulator supports 32respectively aligned with projections 1' through 10, insulators 32 beingsecured to base plate 22 by pins 34 which also serve to connect the endsof the coils to printed circuit conductors carried by base plate 22.

Toroidal coils respectively identified as 1 through 10 are positioned onyoke portion 25 respectively between teeth 1' through 10', as shown inFIG. 2, there being one coil positioned between each adjacent pair ofprojections. Coils 1 through 10 are substantially identical, i.e., eachhaving substantially the same number of turns, and are wound on yokeportion 25 in the same sense.

In accordance with the invention, respective pairs of coils 1 through 10are serially connected to form five identical, angularly displaced,symmetrical field windings respectively having first and second ends.One end of each different winding is connected to a different externalterminal A through E, and the other ends of all the windings areconnected to a common terminal. More particularly, coils l and 4 havingthree adjacent projections l, 2' and 3' therebetween are connected inseries by connection 36-1, end 38-1 of coil 1 being connected toexternal terminal A and end 40-1 being connected by common connection 42to the common terminal, coils I and 4 thus forming the first winding.Similarly, coils 3 and 6 having projections 3', 4 and 5' therebetweenare serially connected by connection 36-2, end 38-2 of coil 3 beingconnected to external terminal B and end 40-2 of coil 6 being connectedto common connection 42, coils 3 and 6 forming the second winding. Coils5 and 8 having projections 5, 6 and 7 therebetween are seriallyconnected by connection 36-3, end 38-3 of coil 5 being connected toexternal terminal C and end 40-3 of coil 8 being connected to commonconnection 42, coils 5 and 8 thus forming the third winding. Coils 7 and10 having projections 7, 8' and 9' therebetween are serially connectedby connection 36-4, end 38-4 of coil 7 being connected to externalterminal D and end 40-4 of coil 10 being connected to common connection42, coils 7 and 10 thus forming the fourth winding. Finally, coils 9 and2 having projections 9', 10' and 1' therebetween are serially connectedby connection 36-5, end 38-5 of coil 9 being connected to externalterminal E and end 40-5 of coil 2 being connected to common connection42, coils 9 and 2 thus forming the fifth winding.

The serially connected pairs of coils which respectively comprise thefield windings are so wound and serially connected that upon connectionof each different external terminal A through E and the common terminalto a source 44 of direct current, the three adjacent projections betweenthe respective pair of coils are excited with the same polarity. Thus,considering coils l and 4 which comprise the first field winding, withexternal terminal A connected to the positive side of source 44 by the Aelement of switch 46 and the common terminal connected to the negativeside thus energizing coils l and 4, the adjacent groups of threeprojections 1', 2' and 3' between coils l and 4 are excited with Northpolarity, all the remaining projections having South polarity, as shownin FIG. 2.

Referring additionally to the stator structure shown in FIG. 6 whichdiffers mechanically from the stator structure shown in FIG. 2 only inthat twelve projections and coils are provided, it will be seen thatwhen two adjacent windings are energized, a group of five adjacentprojections are excited with one polarity, the middle one of the fiveexcited projections having substantially greater magnetic flux densitytherein than the remaining four projections. Thus, with terminals A andB connected by switch elements A and B of switch 46 to the positive sideof source 44 and the common terminal connected to the negative side,coils 1 and 4 comprising the first winding and coils 3 and 6 comprisingthe second winding are energized thus exciting the group of fiveadjacent projections l, 2', 3', 4' and 5 with North" polarity, themiddle projection 3' having substantially higher flux density thereinthan the remaining projections 1, 2', 4' and 5' by virtue of the factthat energized coils 3 and 4 are positioned on either side of projection3'.

Permanent magnet rotor member 48 is mounted on hub 50 rotatablysupported on shaft 23 by bearings 52 spaced-apart by spacer 54. Drum 56preferably formed of suitable plastic material and has inner annularflange portion 58 mounted on hub 50 and outer annular flange portion 60upon which the indicia are displayed. Rotor member 48 is thus mountedfor rotation about axis 62 of shaft 23 concentric with the axis of thebore defined by inner ends 26 of stator projections 1 through 10'.

Permanent magnet rotor member 48 has oppositely polarized, diametricallyopposite ends 64, 66 respectively having substantially the same angularspan 68 as the angular span of inner ends 26 of three adjacent statorprojections. In the position indicator shown in FIGS. 1 through 3, theangular span of inner ends 26 of three adjacent stator projections andangular span 68 of ends 64, 66 of permanent magnet rotor member 48 is93. Opposite ends 64, 66 of of rotor member 48 respectively have polarprojections 70, 72 formed thereon respectively having the same angularspan 74 as the angular span of inner end 26 of one stator projection. Inthe ten position embodiment shown in FIGS. 1 through 3, the angular spanof inner end 26 of one stator projection and the annular span 74 ofrotor member projections 70, 72 is 21. Opposite ends 64, 66 of permanentmagnet rotor member 48 further comprise arcuate surface portions 76respectively extending on opposite sides of projections 70, 72. It willthus be seen that rotor member projections 70, 72 respectively formrelatively small air gaps 78 with inner ends 26 of a diametricallyopposite pair of stator projections, such as projections 2', 7', andthat arcuate surface portions 76 respectively form slightly wider airgaps with inner ends 26 of the remaining ones of two diametricallyopposite groups of three adjacent stator projections, such as l, 3, 6'and 8. Permanent magnet rotor member 48 has side portions 82respectively extending between opposite ends 64, 66 which respectivelyform air gaps 84 with the remaining stator projections intermediate thetwo diametrically opposite groups of three adjacent projections, such asprojections 4, 5', 9' and 10', air gaps 84 being substantially widerthan air gaps 78 and 80.

Referring particularly to FIG. 3, permanent magnet rotor member 48 has ageometric axis 86 extending through rotational axis 62 and respectivelythrough the mid points of polar projections 70, 72. Magnetic axis 88 ofpermanent magnet rotor member 48 also extends through polar projections70, 72 but is angularly displaced from geometric axis 86 on one sidethereof. The train of permanent magnet rotor member 48 is parallel withgrain axis 90 which may be angularly displaced from geometric axis 86 onthe opposite side thereof from magnetic axis 88, as shown. However, thegrain axis may be angularly displaced from the geometric axis 86 on thesame side as magnetic axis 88, or may be coincident with the magneticaxis.

Referring again to FIG. 2, it will now be seen that when a pair ofserially connected coils comprising one winding are energized therebyexciting the group of three adjacent stator projections therebetweenwith one polarity, such as the excitation of adjacent stator projections1, 2 and 3' with North polarity in response to energization of coils land 4, permanent magnet rotor member 48 will rotate to align its South"polarized end 64 with the North polarized stator projections l, 2' and3, rotor member projection 70 being aligned with stator projection 2.Similarly, and referring briefly again to FIG. 6, it will be seen thatwith the coils of two adjacent windings energized thereby exciting agroup of five adjacent stator projections with one polarity, such as theexcitation of adjacent projections 1', 2, 3', 4', 5' with North polarityin response to energization of the serially connected pairs of coils 1and 4 and 3 and 6, permanent magnet rotor member 48 will rotate to alignits South polarized end 64 with the middle three stator projections 2,3, 4, rotor projection 70 being aligned with the middle statorprojection 3' which has the greatestmagnetic flux density therein.

It will now be seen that positive lock-in of permanent magnet rotormember 48 at any selected position is provided, any tendency of rotormember 48 to be bounced to a different position due to vibration therebyproviding a false reading; being eliminated.

Referring now additionally to FIGS. 4A and B, it will be seen that thedesired one or two of five code is provided with the common terminal atall times connected to the negative side of source 44 and the fiveswitch elements A through E of switch 46 selectively actuated to connecteither one only of the external terminals to the positive side of source44 thereby energizing the respective pair of serially connected coils,or to connect the external terminals respectively connected to twoadjacent windings to the positive side of source 44 thereby energizingthe respective two pairs of coils. Thus, as shown in FIGS. 4A and B,with external terminal A and the common terminal respectively connectedto the positive and negative sides of source 44 by element A of switch46, serially connected coils 1 and 4 are energized thereby providing azero reading, and with external terminals A and B connected to thepositive side and the common terminal connected to the negative side ofsource 44 by switch elements A and B of switch 46, coils l and 4, and 3and 6 are energized thereby causing rotor member 48 to rotate to providea one reading.

Referring further to FIG. 5, it will be seen that a one of five reversepolarity code can also be provided by appropriate modification of switch46. Thus, with ter minal A and the common terminal respectivelyconnected to the positive and negative sides of source 44, rotor member48 is rotated to provide a zero reading, and with terminal A and thecommon terminal respectively connected to the negative and positivesides of source 44, rotor member 48 is rotated to provide a fivereading.

While a simple, five position manually actuated switch 46 isschematically shown in FIG. 2, it will be readily understood that asolid state switching system may be employed.

Referring now to FIG. 6 in which like elements are indicated by likereference numerals, it will readily be seen that a one or two of sixcode or one of six reverse polarity code indicator may be providedutilizing the same winding arrangement as shown in connection with theone or two of five code or one of five reverse polarity code embodimentof the previous figures. Herc, stator core structure 24 is provided with12 equally angularly spaced projections 1' through 12' and sixangularlydisplaced, symmetrical windings respectively having ends 38-1 through38-6 connected to external terminals A through F and ends 40-1 through40-6 connected to the common terminal. Again, each of the six fieldwindings comprises two serially connected coils having a group of threeadjacent stator projections therebetween, there being one only coil 1through 12 between each pair of stator projections 1' through 12'. Thus,coils l and 4 having adjacent projections 1' through 3 therbetween areserially connected between external terminal A and the common terminal,coils 3 and 6 having stator projections 3', 4' and 5 therebetween areserially connected between terminal B and the common terminal, coils 5and 8 having projections 4', 6' and 7 ther ebetween are seriallyconnected between terminal C and the common terminal, coils 7 and havingprojections 7, 8 and 9' therebetween are serially connected betweenterminal D and the common terminal, coils 9 and 12 having projections9', 10' and 11 therebetween are serially connected between terminal Eand the common terminal, and coils 11 and 2 having projections 11, 12'and 1 therebetween are serially connected between terminal E and thecommon terminal.

Referring briefly again to FIGS. 2 and 3, side portions 82 of permanentmagnet rotor member 48 are there shown as being formed of two straightsegments 81a, 82b respectively disposed at an angle to geometric axis86, that angle being in the illustrated embodiment. In FIG. 6, sideportions 82' of permanent magnet rotor member 48 are shown as beingrespectively straight between opposite ends 64, 66. The magnetconfiguration of either FIGS. 2 and 3, or FIG. 6 may be employed in anyembodiment of the invention.

Referring briefly to FIG. 7, a one or two of six code is shown for the12 position indicator 92 of FIG. 6. Thus, to provide a ten" reading,external terminal F and the common terminal are respectively connectedto the positive and negative sides of source 44 thereby energizingserially connected coils 11 and 2 to excite the group of three adjacentstator projections 11', 12 and 1' with North" polarity thus causingrotor member 48 to rotate to align its South" end 64 with the threeNorth polarized stator projections 11', 12 and 1', rotor projection 70being aligned with stator projection 12'. Similarly, to provide aneleven reading, terminals A and F are connected to the positive side ofsource 44 and the common terminal to the negative side thus energizingserially connecting coils 11 and 2 and 1 and 4 so as to excite the groupof five adjacent projections 11', 12, 1', 2 and 3' with North polarity,the middle projection 1' having substantially higher magnetic fluxdensity therein than the remaining four projections 11, 12', 2' and 3,thus causing permanent magnet rotor member 48 to rotate to align itsSouth" end 64 with the middle three projections 12', 1', 2', rotorprojection 70 being aligned with the middle stator projection 1. It willalso be readily seen that a one of six reverse polarity code may beprovided by appropriate modification of switch 46.

Referring now to FIG. 8 in which like elements are indicated by likereference numerals, here a 10 position indicator 94 is shown in whicheach of the five field windings comprises three coils 96, 98 and 100respectively positioned on an adjacent group of three statorprojections, ends 38 of the field windings being respectively connectedto external terminals A through E and ends 40 being connected by commonconnection 42 to the common terminal. Further, in this embodiment, themiddle coil 98 of each winding has substantially twice the number ofturns as the two end coils 96, 100. Thus, considering the field windingconnected to external terminal A, coil 96-1 is positioned on statorprojection 1', coil 98-1 is positioned on projection 2', and coil 100-1is positioned on projection 3', coil 98-1 having substantially twice thenumber of turns as coils 96-1 and 100-1. It will further be seen thatthe alternate projections 2', 4, 6, 8' and 10' have only coils 98-1,98-2, 98-3, 98-4 and 98-5 thereon, whereas each of the interveningprojections 1', 3', 5, 7 and 9' respectively have one coil 96 and onecoil 100 thereon. It will be understood that permanent magnet rotormember 48 of the previous figures is rotatably mounted in the boredefined by inner ends 26 of teeth 1' through 10.

Considering now the first field winding comprising coils 96-1, 98-1 and100-1, with terminal A connected to one side of source 44 and the commonterminal connected to the other side, coils 96-1, 98-1, and 100-1 willbe energized thereby exciting the group of adjacent projections 1', 2and 3' with one polarity, such as North. In this embodiment, sincewindings 98 have substantially twice the number of turns as windings 96and 100, projection 2' will have a magnetic flux density thereinsubstantially twice the magnet flux density in projections 1 and 3'.Permanent magnet rotor member 48 will thus rotate to align its South end64 with the North polarized projection 1', 2' and 3, rotor memberprojection being aligned with stator projections 2.

Considering now connection of external terminals A and B respectivelyconnected to two adjacent field windings to one side of source 44 withthe common terminal connected to the other side, serially connectedcoils 96-1, 98-1 and 100-1 comprising the first field winding andserially connected coils 96-2, 98-2 and 100-2 comprising the secondfield winding will be energized thus exciting the group of five adjacentstator projections 1', 2', 3', 4 and 5' with one polarity, such asNorth. Here, with both coils 96-2 and 100-1 on stator projection 3'energized, it will be seen that the middle three projections 2', 3' and4' will respectively have substantially the same magnetic flux densitytherein whereas, the outer two projections 1' and 5 respectively havingonly coils 96-1 and 100-2 thereon energized will have a magnetic fluxdensity therein substantially one-half the magnet flux density in themiddle three projections 2, 3' and 4'. Permanent magnet rotor member 48will thus rotate to align its South end 64 with the middle threeprojections 2', 3' and 4, rotor projection 70 being aligned with statorprojection 3'.

It will readily be seen that the embodiment of FIG. 8 may also beemployed with a one of five reverse polarity code. It will further beseen that with the addition of two stator projections making a total of12 and one additional field winding comprising three serially connectedcoils 96, 98, 100, a 12 position indicator may be provided responding toa one or two of six code or one of six reverse polarity code.

Referring now to FIG. 9 in which like elements are still indicated bylike reference numerals here, each field winding comprises a firstsection having three serially connected coils 102-1, 104-1 and 106-1respectively positioned on a first group of three adjacent statorprojections, and a second section also comprising three seriallyconnected coils 108-1, 110-1 and 112-1 respectively positioned on asecond group ofstator adjacent projections diametrically opposite thefirst group, the first and second winding sections being seriallyconnected. Again, ends 38 of the field winding sections are respectivelyconnected to external terminals A through E and ends 40 are connected tocommon connection 42 and the common terminal.

Considering the first field winding, the first section comprisesserially connected coils 102-1, 104-1 and 106-1 respectively positionedon adjacent stator projections l 2' and 3', end 38-1 connecting externalterminal A to coil 102-1. The second section comprises seriallyconnected coils 108-1, 110-1 and 112-1 respectively positioned onadjacent stator projections 6',

7 and 8 which are respectively diametrically opposite projections 1', 2'and 3. Coil 106-1 of the first section is serially connected to coil112-1 of the second section by connection 114-1 and end 40-1 connectscoil 108-1 to common connection 42. In this embodiment, each of thecoils 102 through 112 has substantially the same number of turns and iswound in the same sense on the respective stator projection. It will nowbe seen that each stator projection has one coil of three differentwindings thereon. Thus, projection 1 has coil 102-1 of the first sectionof the first winding, coil 1111-35 of the second section of the thirdwinding and .coil 106-5 of the first section of the fifth windingthereon, projection 2' has coil 100-4 of the second section of thefourth winding, coil 104-1 of the first section of the first winding andcoil 112-3 of the second section of the third winding thereon, andprojection 3' has coil 102-2 of the first section of the second winding,coil 110-4 of the second section of the fourth winding, and coil 106-1of the first section of the first winding thereon.

Assuming now that terminal A and the common terminal are respectivelyconnected to the opposite sides of source 44, serially connected coils102-1, 104-1, 106-1, 100-1, 110-1 and 112-1 will be energized, firstsection coils 102-1, 104-1 and 106-1 exciting stator projections 1, 2'and 3 with one polarity, such as North," and second section coils 108-1,110-1 and 112-1 exciting projections 6', 7 and 8' with the oppositepolarity, such as South, the remaining projections 4', 9' and 10' beingessentially neutral (with rotor member 48 rotatably positioned in thebore defined by inner ends 26 of projections 1 through 10'). Thus,permanent magnet rotor member 48 will rotate to align its South end 64with the North polarized stator projections l 2' and 3', North end 66 ofrotor member 48 being aligned with the South polarized projections 6',7' and 8. Assuming now that external terminals A and B respectivelyconnected to two adjacent windings are connected to one side of source44 with the common terminal connected to the other side, once againcoils 102-1, 104-1, 106-1, 108-1, 110-1 and 112-1 serially connectedwith external terminal A will be energized, and coils 102-2, 104-2,106-2, 108-2, 110-2 and 112-2 serially connected to external terminal Bare energized. Thus, a first group of five adjacent projections l, 2',3', 4 and 5' are excited with one polarity, such as North and theremaining group of five projections 6', 7, 8', 9' and 10 are excitedwith the opposite polarity, such as South.

With this connection,- it will be observed that with external terminalsA and B energized, one coil only is energized on projections 1', 2, 4',5, 6', 7', 9' and 10, i.e., coils 102-1, 104-1, 104-2, 106-2, 108-1,110-1, 110-2 and 112-2, respectively, whereas two coils are energized onopposite projections 3 and 8', i.e., coils 102-2, 106-1, 108-2 and112-1, respectively. Thus, the opposite middle projections 3', 8' of thetwo groups of five adjacent projections have a magnetic flux densitytherein substantially twice the magnetic flux density in the remainingprojections. Permanent magnet rotor member 48 will thus rotate to alignits South end 64 with projections 2, 3 and 4', its North end 66 beingaligned with projections 7', 8' and 9, rotor projections 70, 72 beingrespectively aligned with stator projections 3', 8.

It will be seen that the embodiment of FIG. 9 may also be employed witha one of five reverse polarity code however, the geometry is such thatthe embodiment of FIG. 9 can be employed only in indicators whereone-half the even number of positions and polar projections is an oddnumber. Thus, the embodiment of FIG. 9 cannot be employed in a twelveposition indicator.

Referring now to FIG. 10 in which like elements are again indicated bylike reference numerals, while the embodiment of the invention shown inFIGS. 2 and 6 employs windings formed of toroidal coils and theembodiments of FIGS. 0 and 9 employ windings formed of salient coils,there is here shown an embodiment em ploying distributed windings. Here,each of the five windings comprises a coil 116 spanning a group of threeadjacent stator projections, end 30 of each winding again beingconnected to an; external terminal A through E and end 40 beingconnected to common connection 42. Thus, coil 116-1. comprising thefirst winding spans projections 1', 2' and 3', coil 116-2 comprising thesecond winding spans projections 3', 4' and 5', coil 116-3 comprisingthe third winding spans projections 5, 6' and 7', coil 116-4 comprisingthe fourth winding spans projections 7', 8 and 9', and coil 116-5comprising the fifth winding spans projections 9, 10 and 1'. Each of thecoils 116 has substantially the same number of turns wound in the samesense. It will be observed that alternate projections 1, 3', 5, 7 and 9are respectively spanned by two coils, i.e., 1 16-1 and 116-5, 116-2 and116-1, 116-3 and 116-2, 116-4 and 116-3, and 116-4 and 116-5,respectively.

Assuming now that external terminal A and the common terminal areconnected to the opposite sides of source 44, coil 116-1 will beenergized thus exciting the group of three adjacent stator projections1', 2' and 3' with one polarity, such as North. Thus, permanent magnetrotor member 48 will rotate to align its South" end 64 with the group ofthree North polarized projections 1', 2' and 3, rotor projection beingaligned with stator projection 2.

Assuming now that external terminals A and B respectively connected tothe two adjacent windings 116-1 and 116-2 are connected to one side ofsource 44 with the common terminal connected to the other side, coils116-1 and 116-2 will be energized thus exciting the group of fiveadjacent stator projections 1, 2', 3', 4 and 5 with one polarity, suchas North." Here it will be observed that since the middle projection 3'of the group of five projections is spanned by both energized coils116-1 and 116-2, projection 3' will have substantially twice themagnetic flux density therein as the remaining projections 1', 2', 4 and5. Thus, permanent magnet rotor member 40 will rotate to align its Southend 64 with the middle three North polarized projections 2', 3 and 4',rotor projections 70 being aligned with stator projection 3' which hasthe highest magnetic flux density therein.

It will be observed that the arrangement shown in FIG. 10 may also beemployed with a one of five reverse polarity code. It will further beobserved that the arrangement shown in FIG. 10 may be employed in atwelve position indicator by the :mere addition of two statorprojections and one additional winding 116.

Referring now to FIG. 11 in which like elements are still indicated bylike reference numerals, here each of the field windings comprises twoserially connected coils 118 and 120, each spanning two statorprojections of a group of three adjacent projections, the middleprojection of the group being spanned by both coils. Each of the coils118, 120 has the same number of turns and is wound in the same sense.

Assuming now that external terminal A and the common terminal areconnected to the opposite sides of source 44, serially connected coils1l81 and 120-1 comprising the first winding will be energized thusexciting the group of three adjacent stator projections 1, 2' and 3'with one polarity, such as North, it being observed that since bothcoils 118-1 and 1204 span the middle projection 2, that projection willhave a magnetic flux density therein substantially twice the magnet fluxdensity in projections 1' and 3'. Thus, permanent magnet rotor member 48will rotate to align its South end 64 with the group of three Northpolarized projections 1, 2' and 3', rotor projection 70 being alignedwith stator projection 2.

Assuming now that terminals A and B respectively connected to the twoadjacent field windings are connected to one side of source 44 with thecommon terminal connected to the other side, serially connected coils1181 and l20-1 comprising the first field winding and serially connectedcoils 118-2 and 120-2 comprising the second field winding are energizedthus exciting a group of five adjacent stator projections 1', 2', 3', 4and 5 with one polarity, such as North, it being observed that themiddle three projections 2', 3' and 4' will each have a magnetic fluxdensity therein substantially twice the magnetic flux density in theouter projections l and 5 since each of the middle three projections isspanned by two energized coils whereas the outer two projections arerespectively spanned by one only energized coil. Thus, permanent magnetrotor member 48 will rotate to align its South end 64 with the middlethree North polarized projections 2', 3 and 4', rotor projection 70being aligned with stator projection 3'.

It will be seen that the arrangement shown in FIG. 11 may also beemployed with a one of five reverse polarity code. It will further beseen that the arrangement shown in FIG. 11 may be embodied in a 12position indicator by adding two additional stator projections and oneadditional field winding comprising two serially connected coils 118,120.

While there have been described above the principles of this inventionin connection with specific apparatus, it is to be clearly understoodthat this description is made only by way of example and not as alimitation to the scope of the invention.

What is claimed is:

1. A rotary magnetic position indicator for displaying a predeterminedeven number of discrete indicia, said indicator comprising: a magneticstator core structure having a yoke portion with said even number ofpolar projections extending radially inwardly therefrom, saidprojections being equally angularly spaced around said yoke portion andhaving radially inner ends defining a bore; a magnetized, geometricallysymmetrical rotor member mounted in said bore for rotation about an axisconcentric therewith and having two only oppositely polarizeddiametrically opposite ends, each of said opposite ends having anangular span generally equal to the angular span of said inner ends ofthree only adjacent projections and forming air gaps therewith; and aplurality of substantially identical field windings equal in number toone-half said even number and each having first and second ends, saidwindings being positioned on said core structure in angularly displacedsymmetrical relationship, each of said windings having its first endconnected to a different external terminal adapted to be selectivelyconnected to one side of a source of direct current potential, saidsecond ends of all of said windings being connected to a common terminaladapted to be connected to the other side of said source; thearrangement of said windings being such that upon connection of eachdifferent one of said external terminals and said common terminal tosaid source and energization of the respective windings thereby, adifferent group of three adjacent projections are excited with onepolarity thereby causing said rotor member to rotate to align theopposite polarity end thereof with the respective group of threeprojections, and that upon connection of the external terminalsrespectively connected to each different pair of adjacent windings andsaid common terminal to said source and energization of the respectivepair of adjacent windings thereby, a different group of five adjacentprojections are excited with one polarity with at least the middle oneof said group of five projections having a higher magnetic flux densitytherein than the outer two of said group of five projections therebycausing said rotor member to rotate to align the opposite polarity endthereof with the middle three of the respective group of fiveprojections, thereby providing said even number of discrete magneticorientations for said rotor member.

2. The indicator of claim 1 wherein said rotor member comprises apermanent magnet.

3. The indicator of claim 1 wherein said rotor member has opposite sidesrespectively extending between said opposite ends, said sides formingthe air gaps with said inner ends of the remaining projections, saidother air gaps being substantially wider than the air gaps formed bysaid opposite ends.

4. The indicator of claim 3 wherein each of said opposite ends of saidrotor member has a polar projection thereon forming a first air gap withthe middle one of the respective three adjacent stator structureprojections with surface portions on opposite sides thereof respectivelyforming second air gaps with the outer two of the respective threeadjacent stator structure projec tions, said second air gaps being widerthan said first air gaps.

5. The indicator of claim 4 wherein said rotor member comprises apermanent magnet, said rotor member having a geometric axis extendingthrough the center of said rotor member polar projections, said rotormember having a magnetic axis also extending through said rotor memberpolar projections and angularly displaced from said geometric axis onone side thereof, said permanent magnet having a grain axis angularlydisplaced from said geometric axis.

6. The indicator of claim 1 wherein the arrangement of said windings issuch that upon connection of the external terminals respectivelyconnected to each different pair of adjacent windings and said commonterminal to said source and energization of the respective pair ofadjacent windings thereby, the middle one of the respective group offive projections has a higher magnetic flux density therein than theremaining projections of said group of five projections.

7. The indicator of claim 1 wherein each of said windings comprises twocoils connected in series.

8. The indicator of claim 7 wherein said coils are positioned on saidyoke portion, there being one only coil positioned between eachdifferent pair of said projections, the two coils of each differentwinding having a said different group of three said adjacent projectionstherebetween and excited thereby.

9. The indicator of claim 1 wherein each of said windings comprisesthree coils connected in series, the three coils of each differentwinding being respectively positioned on a said different group of threeadjacent projections and respectively exciting the same.

10. The indicator of claim 9 wherein alternate projections respectivelyhave one coil of one winding and one coil of an adjacent windingthereon, said alternate projections respectively being the middle onesof said different groups of five projections.

11. The indicator of claim 10 wherein the middlecoil of each winding hastwice the number of turns as the two end coils, said end coils beingrespectively positioned on said alternate projections.

12. The indicator of claim 1 wherein each of said windings comprises afirst serially connected group of three coils and a second seriallyconnected group of three coils with said first and second groups beingconnected in series, each different winding having the three coils ofits first group respectively positioned on a said different group ofthree adjacent projections and respectively exciting the same with onepolarity, and having the three coils of its second group respectivelypositioned on another group of three adjacent projections respectivelydiametrically opposite said firstnamed group of projections andrespectively exciting the same with the opposite polarity, each saidprojection having one coil of each of three said groups of coilsthereon.

13. The indicator of claim 1 wherein each different one of said windingscomprises a coil embracing a said different group of three adjacentprojections and exciting the same, alternate projections being embracedby said coils of two adjacent windings and respectively being the middleones of said different groups of five projections.

14. The indicator of claim 1 wherein each different one of said windingscomprises first and second coils connected in series respectivelyembracing the two outer and the middle projections of a said differentgroup of three adjacent projections and exciting the same.

15. In a rotary magnetic position indicator for displaying apredetermined even number of discrete indicia and including a magneticstator core structure having a yoke portion with said even number ofpolar projections extending inwardly therefrom, said projections beingequally angularly spaced around said yoke portion and having radiallyinner ends defining a bore; a magnetized geometrically symmetrical rotormember mounted in said bore for rotation about an axis concentrictherewith and having two only oppositely polarized diametricallyopposite ends, each of said opposite ends having an angular spangenerally equal to the angular span of three only adjacent projectionsand forming air gaps therewith.

16. The indicator of claim 15 wherein said rotor member comprises apermanent magnet.

17. The indicator of claim 15 wherein said rotor member has oppositesides respectively extending between said opposite ends, said sidesforming other air gaps with said inner ends of the remainingprojections, said other air gaps being substantially wider than the airgaps formed by said opposite ends.

18. The indicator of claim 15 wherein each of said opposite ends of saidrotor member has a polar projection thereon forming a first air gap withthe middle one of the respective three adjacent stator structureprojections with surface portions on opposite sides thereof respectivelyforming second air gaps with the outer two of the respective threeadjacent stator structure projections, said second air gaps being widerthan said first air gaps.

19. The indicator of claim 18 wherein said rotor member comprises apermanent magnet, said rotor member having a geometric axis extendingthrough the center of said rotor member polar projections, said rotormember having a magnetic axis also extending through said rotor memberpolar projections and angularly displaced from said geometric axis onone side' thereof, said permanent magnet having a grain axis angularlydisplaced from said geometric axis.

1. A rotary magnetic position indicator for displaying a predeterminedeven number of discrete indicia, said indicator comprising: a magneticstator core structure having a yoke portion with said even number ofpolar projections extending radially inwardly therefrom, saidprojections being equally angularly spaced around said yoke portion andhaving radially inner ends defining a bore; a magnetized, geometricallysymmetrical rotor member mounted in said bore for rotation about an axisconcentric therewith and having two only oppositely polarizeddiametrically opposite ends, each of said opposite ends having anangular span generally equal to the angular span of said inner ends ofthree only adjacent projections and forming air gaps therewith; and aplurality of substantially identical field windings equal in number toone-half said even number and each having first and second ends, saidwindings being positioned on said core structure in angularly displacedsymmetrical relationship, each of said windings having its first endconnected to a different external terminal adapted to be selectivelyconnected to one side of a source of direct current potential, saidsecond ends of all of said windings being connected to a common terminaladapted to be connected to the other side of said source; thearrangement of said windings being such that upon connection of eachdifferent one of said external terminals and said common terminal tosaid source and energization of the respective windings thereby, adifferent group of three adjacent projections are excited with onepolarity thereby causing said rotor member to rotate to align theopposite polarity end thereof with the respective group of threeprojections, and that upon connection of the external terminalsrespectively connected to each different pair of adjacent windings andsaid common terminal to said source and energization of the respectivepair of adjacent windings thereby, a different group of five adjacentprojections are excited with one polarity with at least the middle oneof said group of five projections having a higher magnetic flux densitytherein than the outer two of said group of five projections therebycausing said rotor member to rotate to align the opposite polarity endthereof with the middle three of the respective group of fiveprojections, thereby providing said even number of discrete magneticorientations for said rotor member.
 2. The indicator of claim 1 whereinsaid rotor member comprises a permanent magnet.
 3. The indicator ofclaim 1 wherein said rotor member has opposite sides respectivelyextending between said opposite ends, said sides forming other air gapswith said inner ends of the remaining projections, said other air gapsbeing substantially wider than the air gaps formed by said oppositeends.
 4. The indicator of claim 3 wherein each of said opposite ends ofsaid rotor member has a polar projection thereon forming a first air gapwith the middle one of the respective three adjacent stator structureprojections with surface portions on opposite sides thereof respectivelyforming second air gaps with the outer two of the respective threeadjacent stator structure projections, said second air gaps being widerthan said first air gaps.
 5. The indicator of claim 4 wherein said rotormember comprises a permanent magnet, said rotor member having ageometric axis extending through the center of said rotor member polarprojections, said rotor member having a magnetic axis also extendingthrough said rotor member polar projections and angularly displaced fromsaid geometric axis on one side thereof, said permanent magnet having agrain axis angularly displaced from said geometric axis.
 6. Theindicator of claim 1 wherein the arrangement of said windings is suchthat upon connection of the external terminals respectively connected toeach different pair of adjacent windings and said common terminal tosaid source and energization of the respective pair of adjacent windingsthereby, the middle one of the respective group of five projections hasa higher magnetic flux density therein than the remaining projections ofsaid group of five projections.
 7. The indicator of claim 1 wherein eachof said windings comprises two coils connected in series.
 8. Theindicator of claim 7 wherein said coils are positioned on said yokeportion, there being one only coil positioned between each differentpair of said projections, the two coils of each different winding havinga said different group of three said adjacent projections therebetweenand excited thereby.
 9. The indicator of claim 1 wherein each of saidwindings comprises three coils connected in series, the three coils ofeach different winding being respectively positioned on a said differentgroup of three adjacent projections and respectively exciting the same.10. The indicator of claim 9 wherein alternate projections respectivelyhave one coil of one winding and one coil of an adjacent windingthereon, said alternate projections respectively being the middle onesof said different groups of five projections.
 11. The indicator of claim10 wherein the middle coil of each winding has twice the number of turnsas the two end coils, said end coils being respectively positioned onsaid alternate projections.
 12. The indicator of claim 1 wherein each ofsaid windings comprises a first serially connected group of three coilsand a second serially connected group of three coils with said first andsecond groups being connected in series, each different winding havingthe three coils of its first group respectively positioned on a saiddifferent group of three adjacent projections and respectively excitingthe same with one polarity, and having the three coils of its secondgroup respectively positioned on another group of three adjacentprojections respectively diametrically opposite said first-named groupof projections and respectively exciting the same with the oppositepolarity, each said projection having one coil of each of three saidgroups of coils thereon.
 13. The indicator of claim 1 wherein eachdifferent one of said windings comprises a coil embracing a saiddifferent group of three adjacent projections and exciting the same,alternate projections being embraced by said coils of two adjacentwindings and respectively being the middle ones of said different groupsof five projections.
 14. The indicator of claim 1 wherein each differentone of said windings comprises first and second coils connected inseries respectively embracing the two outer and the middle projectionsof a said different group of three adjacent projections and exciting thesame.
 15. In a rotary magnetic position indicator for displaying apredetermined even number of discrete indicia and including a magneticstator core structure having a yoke poRtion with said even number ofpolar projections extending inwardly therefrom, said projections beingequally angularly spaced around said yoke portion and having radiallyinner ends defining a bore; a magnetized geometrically symmetrical rotormember mounted in said bore for rotation about an axis concentrictherewith and having two only oppositely polarized diametricallyopposite ends, each of said opposite ends having an angular spangenerally equal to the angular span of three only adjacent projectionsand forming air gaps therewith.
 16. The indicator of claim 15 whereinsaid rotor member comprises a permanent magnet.
 17. The indicator ofclaim 15 wherein said rotor member has opposite sides respectivelyextending between said opposite ends, said sides forming other air gapswith said inner ends of the remaining projections, said other air gapsbeing substantially wider than the air gaps formed by said oppositeends.
 18. The indicator of claim 15 wherein each of said opposite endsof said rotor member has a polar projection thereon forming a first airgap with the middle one of the respective three adjacent statorstructure projections with surface portions on opposite sides thereofrespectively forming second air gaps with the outer two of therespective three adjacent stator structure projections, said second airgaps being wider than said first air gaps.
 19. The indicator of claim 18wherein said rotor member comprises a permanent magnet, said rotormember having a geometric axis extending through the center of saidrotor member polar projections, said rotor member having a magnetic axisalso extending through said rotor member polar projections and angularlydisplaced from said geometric axis on one side thereof, said permanentmagnet having a grain axis angularly displaced from said geometric axis.